Imagine a box, similar to a Wi-Fi router, that sits in your home and tracks all kinds of physiological signals as you move from room to room: breathing, heart rate, sleep, gait, and more.

Dina Katabi, a professor of electrical engineering and computer science at MIT, built this box in her lab. And in the not-so-distant future, she believes, it will be able to replace the array of expensive, bulky, uncomfortable gear we currently need to get clinical data about the body.

Speaking at MIT Technology Review’s EmTech conference in Cambridge, Massachusetts, on Wednesday, Katabi said the box she’s been building for the last several years takes advantage of the fact that every time we move—even if it’s just a teeny, tiny bit, such as when we breathe—we change the electromagnetic field surrounding us.

Her device transmits a low-power wireless signal throughout a space the size of a one- or two-bedroom apartment (even through walls), and the signal reflects off people’s bodies. The device then uses machine learning to analyze those reflected signals and extract physiological data. So far, it has been installed in over 200 homes of both healthy people and those with conditions like Parkinson’s, Alzheimer’s, depression, and pulmonary diseases, she said. Katabi cofounded a startup called Emerald Innovations to commercialize the technology and has already made the device available to biotech and pharmaceutical companies for studies.

To illustrate how this could be helpful, Katabi also showed off data gathered over eight weeks in the home of a Parkinson’s patient, indicating that his gait improved around 5 or 6 each morning—right around the time he took his medication.

“Not only do you start understanding the life of the patient, but you start understanding the impact of the medication,” she noted. That could also help doctors figure out how some medications help certain patients but not others.

Katabi said her research found that the device can accurately monitor sleep, including individual sleep stages, in a person’s own bed, with no changes to the way they sleep or what they wear—a big difference from sleep studies today, which typically call for snoozing in a lab setting with a lot of electrodes and wires connected to your body. Because the device would be installed in a home, it could track the resident over time, too, which could be useful for watching sleep-disrupting conditions like Alzheimer’s or depression, she said.

It might sound alarming to have anything in your home that is constantly tracking you: it could be ripe for snooping or other kinds of abuse. Katabi said data is collected only about specific traits and only with a person’s consent. In addition, it is encrypted and is limited to certain designated recipients. And don’t worry about a rogue neighbor pointing this box in your direction: Katabi said the setup process requires a user to complete a series of specific movements before it’s possible to be tracked, so it would be very difficult to secretly follow an unwilling participant.

While Katabi is currently focused on health-care applications for the data, she’s also considering how it could be used for other things, like fine-tuning your smart home so when you sit on the couch, your smart TV could play your favorite show.